Although it is now widely recognized that sperm morphology is the semen characteristic most correlated with fertility and, in particular, fertilizing ability in vitro, many workers remain confused about the origins and specific features of the various criteria and classification schemes used to assess human sperm morphology.The purpose of this article is to review the origins and history of the two major, and often apparently opposing, scoring systems: those of the World Health Organization (WHO) and the Tygerberg Strict Criteria.The similarities and differences between these two approaches will be discussed and their application compared. What Is a Normal Human Spermatozoon?In the earliest reports on human sperm morphology, the ''normal'' or ''typical'' spermatozoon was described as the modal form, ie, the shape that occurred most often.Briefly, these authors focused on the sperm head, describing it as being oval with a smooth contour and divided into anterior ''acrosomal'' and posterior ''postacrosomal'' regions, adding that there should be a single tail with a symmetric axial attachment at the sperm neck, where the proximal part of the tail was thickened in the midpiece region.Regardless of any other considerations, such as whether morphological abnormalities were prioritized in order of head, neck, midpiece, or tail regions or whether defects were assessed multiparametrically, one difference between the past and present is immediately obvious: if